Australia’s first outbreak of a highly pathogenic bird flu virus in 15 years should be contained by a cull of 50,000 chickens, authorities said on Friday, although they don’t know what caused the case at an egg farm in New South Wales state.

The Department of Primary Industries said all the chickens at the property in Maitland, 160 kilometres north of Sydney, would be destroyed after the H7 virus was detected last week.

The H7 strain is highly pathogenic to birds but is not related to the H5N1 strain, which was first detected in 1997 in Hong Kong and has since killed 366 people worldwide.

The department’s chief veterinary officer, Ian Roth, said the strain did not present any risks to food safety from poultry and eggs.

The owners of the infected farm have been quarantined as experts try to find the source of the virus, often wild birds.

“It generally spreads by the movement of birds from the farm and there certainly hasn’t been any of those,” Roth told Australian Broadcasting Corporation radio.

“We’re in the process now of doing the tracing and also surveillance in the area, and so far the tracing looks quite good. There hasn’t been much potential for spread,” he said.

Australia’s Chicken Meat Federation said the industry produced around 1.12 million tonnes a year, worth A$1.9 billion (HK$15.23 billion), with most used domestically and only about 5 per cent exported.

Japan banned the import of poultry and eggs from Australia after the outbreak, the country’s Ministry of Agriculture said on Thursday.

Japan imported 0.9 tonnes of meat last year and 1.9 tonnes in the two years before. Imports of eggs totalled 2.1 tonnes in the three years through to last year. Japan is asking Australian authorities to provide more details about the outbreak.

Chicken Meat Federation executive director Andreas Dubs said most exports were for pet food, while chicken feet were exported to some countries where they are eaten by humans.

The Australian government’s official commodities forecaster expects about 41,000 tonnes of chicken to be exported in the financial year to June 30, next year.

Major export destinations are Hong Kong, Papua New Guinea, the Philippines, Vietnam and South Africa. Producers typically earn about A$1 per kilogram for chicken products.

Many countries, including Japan, have automatic measures to stop imports when there is an outbreak of bird flu and they will be in discussions with Australian authorities to check if the outbreak is contained and exports can be restored.

“It is a fairly normal thing for countries. When you have an outbreak, a number of countries have requirements that you are free of bird flu,” Dubs said. “It is a short-term reaction. It is not really a longer-term concern for us.”

South Korea, which imported 5.2 tonnes of Australian poultry last year, is conducting a review, an official said.

“The ministry is discussing whether to ban Australian poultry imports, though the volume is minimal. After reviewing the issue, we’ll take appropriate safety and sanitary measures,” said Chang Jae-hong, an official from the quarantine policy division at the South Korean agriculture ministry.

Hong Kong has not issued a ban on imports. Beijing also has not issued a ban, but analysts said mainland China was not a major poultry importer from Australia.

Australia faced an outbreak of bird flu in February that led to a ban on Australian exports of poultry products to Japan, but that was not a highly pathogenic virus.

Most bird flu viruses do not cause disease in humans. At least one type of H7 strain, the H7N7 subtype, can infect people and even kill, but the impact on humans usually tends to be mild, the World Health Organisation said.